Publications

Sulfate is often touted as containing atmospheric oxygen whose isotopic signature can constrain redox, environmental conditions, and biological activity. Yet, the amount and isotopic fractionation associated with air-O2 incorporation during sulfate formation is still debated, making its verification difficult. In this study, we identify a distinct, microbially dominated environment with...

Supporting the overarching goal to evaluate critical minerals nationwide, the mine waste characterization effort in the U.S. Geological Survey (USGS) Earth Mapping Resources Initiative has created a series of protocols to standardize sampling carried out under this effort by the participating State geological surveys and their cooperators. The protocols are based on published, reviewed...

Source apportionment of per- and polyfluoroalkyl substances (PFAS) in rivers is typically based on water concentrations, which cannot quantify PFAS loads or define geographical source areas. This study applied a river catchment-scale approach to identify PFAS source zones and assess the relative importance of industrial PFAS sources in the River Mersey, UK – a post-industrial, densely...

Desert dunes are often assumed to have uniform mineral compositions due to extensive mixing during lateral transport, which complicates provenance studies. The Mu Us Sandy Land in north-central China, near the East Asian summer monsoon precipitation boundary, experiences a wetter climate than most deserts. Climate wetting as a result of a warming climate, and the ‘Sand Control Project’...

Gold, antimony, and tungsten resources of the Stibnite-Yellow Pine district, Idaho, are hosted in complexly faulted Late Cretaceous Atlanta Lobe of the Idaho batholith and surrounding Neoproterozoic-Paleozoic metamorphic rocks. This study utilizes detailed petrography and trace element chemistry of quartz to establish relative timing relationships between successive ore forming events...

Ore-genesis, texture, chemical compositions, and thermometry of magnetite were used to better evaluate the origins of iron ore deposits across the Iron Spring district, Utah. Trace element compositions, determined by LA-ICP-MS, were used to calculate temperatures based on XMg numbers and characterize the trace element signatures of magmatic and hydrothermal magnetite. Magnetite occurs as...

Hydrothermal graphite veins are a possible source for modern battery materials and require better understanding of their carbon source(s) and absolute timing to develop mapable criteria for exploration models. We present new observations of graphite vein and alteration paragenesis and U-Pb LA-ICP-MS titanite age data from the Ruby prospect, Montana, USA, that constrain mineralization...

Re-Os geochronology is a powerful tool to directly date sulphide mineralisation using phases such as molybdenite, pyrite and chalcopyrite. We present a snapshot of a method in development utilizing laser ablation inductively coupled-plasma ‘triple quad’ mass spectrometry (LA-ICP-MS/MS) for Re-Os geochronology of molybdenite. While traditional LA-(MC)-ICP-MS measurements are limited by...

The 40Ar/39Ar geochronology method is used to date potassium-bearing rocks and minerals, based on the decay of 40K to 40Ar, which provides important temporal constraints for geological events. The USGS Denver Argon Geochronology Laboratory dates samples from a variety of projects, mainly in the USGS Mineral Resource Program and the National Cooperative Geologic Mapping Program...

The Philipsburg mining district is a Mo-Cu porphyry system with associated Cordilleran polymetallic veins. Geochronology was employed to date the porphyry (~66 Ma, U/Pb in zircon) and molybdenite mineralization from the veins (~76 Ma, Re-Os). Age results suggest that the two-mineralization events model proposed by Lund et al. (2018) for the Butte district can be applied to the...

Carbonatites host most of the global rare earth element (REE) deposits. The petrogenesis of these rocks, including magmatic and post-magmatic processes, are poorly understood but critical in forming and upgrading these deposits. The Mountain Pass carbonatite, which hosts the only active REE mine in North America, is lithologically variable but consistently contains >50% calcite and/or...

A mineral systems approach to mineral exploration provides a comprehensive framework for understanding ore deposit formation by examining the geodynamic, magmatic, hydrothermal, and sedimentary processes responsible for mineralization, alteration, and remobilization of economic mineral deposits. Temporal and thermal constraints on ore genesis are crucial for refining mineral system...